The invention relates to improvements in devices for separably securing one end portion of a first tube to a second tube. The first tube can constitute a hose and the improved devices then constitutes hose couplings which can separably but sealingly secure the one end portion of the hose to a metallic or plastic nipple, e.g., under the hood of or elsewhere in a motor vehicle.
Hose couplings of the type to which the present invention pertains are disclosed, for example, in commonly owned U.S. Pat. No. 4,708,375 granted Nov. 24, 1987 to Heinz Sauer for "Hose coupling" and in commonly owned U.S. Pat. No. 4,786,085 granted Nov. 22, 1988 to Heinz Sauer and Wilfried Heise. These patents disclose couplings wherein one end portion of a hose is clamped between two tubular connecting elements one of which can be detachably coupled to a second tube. The clamping action is rather pronounced in order to prevent leakage of fluid between the one end portion of the hose and the one connecting element. A sealing ring is interposed between the other connecting element and the second tube to thus prevent leakage of confined fluid between the one end portion of the hose and the second tube. The clamping action is or can be so pronounced that it actually equals a bond between the one end portion of the hose and at least one of the connecting elements. Male and female coupling members are provided on the one connecting element and on the second tube to ensure that the one connecting element can be releasably attached to the second tube in response to rotation of the one connecting element relative to the second tube, i.e., the one end portion of the hose must be rotated with the connecting elements. This can create problems if the other end portion of the hose is non-rotatably connected to another part, e.g., to a second nipple; it is then necessary to subject the hose to torsional deforming stresses which can affect the integrity and can shorten the useful life of the hose. Moreover, twisting of the hose necessitates the exertion of a substantial force, even if the hose is made of rubber or another highly elastomeric material. The situation is aggravated if the hose is made of a relatively hard plastic material, e.g., polyamide, polyoxymethylene, polypropylene or polyvinyl chloride. Such hoses cannot be twisted at all. Disengagement of the hose coupling again necessitates the application of torsional stresses because the one end portion of the hose cannot rotate relative to the connecting elements or vice versa.
A somewhat similar hose coupling is disclosed in German Pat. No. 32 31 950 granted May 29, 1991 to Rene Iff. This coupling also employs means for mechanically clamping one end portion of an elastomeric hose between two rigid connecting elements one of which can be separably coupled to a nipple.